A new flexible postage-stamp-sized generator device that converts muscle movements into enough power for small electronics, using human skin as one of its charge-collectors has been developed by researchers at the National University of Singapore. This device takes advantage of static electricity to convert mechanical energy into electrical energy.
Researchers demonstrated that the new device, which can generate 90 volts of open circuit voltage and power of 0.8mW when touched gently with a finger, can be used as a wearable self-powered sensor to track the user's motion and activity. Such friction-powered generators could usher new types of wearable sensors that do not require batteries but instead are powered by the wearer's daily activities like walking, talking or holding an object.
This friction-inducing phenomenon is called the triboelectric effect, and electrical charge builds up on two dissimilar surfaces when they are put in close contact. A potential difference is generated and a current starts flowing between when they are pulled apart or flexed. This current can be collected using an electrode.
Researcher Lokesh Dhakar said, "Skin, the most abundant surface on a human body, is a natural choice for one of the triboelectric layers and also skin as a triboelectric material has a high tendency to donate electrons or get positively charged which is important in improving the performance of the device if the other triboelectric layer intentionally chosen as the one with a tendency to get negatively charged." The device could light up twelve commercial LEDs.